The present invention relates to a novel thermistor, and more particularly to a sensor using an organophosphazene polymer as a thermo-responsive material.
It may safely be said that almost all of semiconductors which have brought about a revolution in the field of electronics are semiconductors made of inorganic materials, including metals and metal oxides, and such ceramic semiconductors have been employed for a variety of purposes. Thermo-sensors presently used are chiefly those using ceramic semiconductors as temperature-detecting materials.
However, such ceramic thermistors have the defect that the yield is not good, since the ceramic semiconductors are sintered bodies of metals or metal oxides and accordingly it is difficult to prepare the thermistors having the same efficiency at all times. This defect has been gradually overcome with increase of uses of ceramic semiconductors, but is not still satisfactory.
On the other hand, a high efficiency has been required for thermo-sensors with development of electronic industry. Ceramic thermistors leave a room for improvement in that thermo-sensor elements of desired shapes are hard to be obtained due to sintered bodies and the application apt to be limited to points, that ceramic thermistors have the limit, due to their property, in making them light weight which is required in electronic industry aiming at lightening and miniaturization, and that the thermistor constant is at most 5,000 K. and accordingly the sensitivity is not satisfactory as well as the reliability in use for a long term and molding processability.
In view of these points, new materials adoptable as thermo-sensors are pursued. It has been attempted to utilize plastics as thermistor materials in place of ceramics, and there are proposed a process in which a semiconductive material is incorporated in usual plastics and the blend is formed into a desired shape, and a process in which a charge-transfer complex is made into a high polymer. The former has the disadvantages that the incorporation of ceramics or analogous materials into plastics accompanies technical difficulty and the efficiency as thermistors of the product is far inferior to that of ceramic thermistors. On the other hand, the latter has a problem in durability of the product. Also, plastic thermistors have the defect that heat resistance and flame resistance are poor. Further, in recent years, an intense study of organic semiconductors such as polyacetylene has been made, but does not go beyond the fundamental study.
It is an object of the present invention to provide a novel thermistor which has no defects as mentioned above.
A further object of the present invention is to provide a thermistor which is good in molding processability, yield of product and reliability.
These and other objects of the present invention will become apparent from the description hereinafter.